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History of Geology

The term geology was first used in the late 18th Century. Although geology was not mentioned in the Encyclopedia Britannica before 1800, by 1809 geology had a lengthy entry. During the earliest days of geological study, mainstream scientific geology was divided into three camps: Plutonists, Neptunists and Catastrophists. At the time the vast majority of all geologists then were theists and much of early geology was correctly based upon the biblical history, utilising and expanding on Biblical scientific foreknowledge. Unsurprisingly, the Plutonists knew that God created the Earth, but that volcanoes and fire had recently shaped the modern world. The Neptunists also knew that the ocean and the Great Flood were a primary factor in geology.[1][2][3] Catastrophists, on the other hand, believed that the Earth had been created by God in one great catastrophe. Thus, Catastrophists concluded that everything which we now see was much the same as the world was at Creation.

In 1775, during the liberalatheistic "enlightenment", James Hutton presented a thesis, Theory of the Earth, to the Royal Society of Edinburgh. Hutton, who is considered by some to be the father of modern geology, attempted to explain the rationale for his conclusion that the Earth must be much older than it really is. Coupling observation with junk science, he believed that the Earth must be very old indeed. In every direction he looked Hutton thought he saw evidence of eroded mountains, dry land which had once been sea, and sediment and rocks at the bottom of the ocean. After ten years of study he published his findings in his book Theory of the Earth to document his claims of a much older Earth.[4][5]

Dismissed at the time as nonsense, atheists now willingly accept Hutton's conclusions claiming that they were borne out by observations collected from around the world during the rise of the British Empire and in the Royal Geographic Society. Taken in by that, in 1830, Sir Charles Lyell published the first of what would eventually grow into twelve editions of Principles of Geology. Charles Lyell reported geological processes occurring every day. He then claimed to have documented geological process which have occurred during the recorded history of man. By inference he concluded that geological processes must have occurred before the recorded history of man.[6][7] In time, atheist geologists came to agree with his theory of uniformitarianism.

Modern geologists know much about the Earth and geologic processes. Volcanism and deformation bring rocks to the surface of the Earth from depths as great as 50 to 100 km. Scientists can make inferences about some of the properties of the Earth at these depths by studying these rocks. But far more information has been provided through the use of seismic waves created by natural earthquakes, and by controlled explosions designed to learn more about the composition of the Earth, including underground nuclear explosions. This data has revealed that the Earth is composed of three main layers, the crust, the mantle and the core. The crust, or outermost layer, varies in thickness from about 5 km under oceans to about 40 km under continents. The mantle consists of an outermost zone of about 100 km thick named the lithosphere. The layer below is a partially fluid solid named the athenosphere, which ends at a depth of about 200 km. As seismic waves penetrate deeper into the mantle they indicate that between 400 km and about 2900 km atoms are packed closer and closer together by extreme pressures, creating a crystalline structure. The Earth's core is 2900 km from the surface. Seismic waves slow down in this region until a depth of 5100 km, indicating that the core consists of a liquid layer surrounding a solid core at the center.[8]

Extensive exploration and mapping of the seafloor after World War II led to the discovery of a deep rift running down the center of the Mid-Atlantic Ridge. In the early 1960s Harry Hess of Princeton University and Robert Dietz of the University of California suggested that the seafloor separates along the rifts in mid-0ceanic ridges and that new seafloor forms by upwelling of hot mantle materials in these cracks, followed by lateral spreading. By 1967 separate lithospheric plates had been identified, which explained phenomena such as high levels of volcanic and earthquake activity that take place between the plates. By the end of the 1960s the theory of plate tectonics proved to be a unifying concept that pulled together diverse theories and explained a the large body of observations in the field.[8]

Twelve or so plates slide over a partially molten lithosphere, and the continents, embedded in some of the plates, are carried by them. Where plates collide, mountains such as the Himalayas or the Rocky Mountains are formed. In some places, called subduction zones, one plate sinks beneath another plate and returns to the molten regions of the athenosphere. Along mid-oceanic ridges magma emerges to expand the plate and create new sea floor.

Planetary geology (sometimes known as Astrogeology) refers to the application of geologic principles to other bodies of the solar system. However, specialised terms such as selenology (studies of the Moon), areology (of Mars), etc., are also in use.